What Foods Are High in Oxalate (Oxalic Acid)? Kidney Stone Prevention

Medically Reviewed on 1/5/2022
What Foods Are High in Oxalate (Oxalic Acid)
Foods high in oxalate (oxalic acid) include spinach, firm tofu, soy milk, potatoes, beets, raspberries, navy beans, almonds, and dates

Oxalates, also called oxalic acid, is a concern for people with kidney disease or kidney stones. In high amounts, oxalates can bind with calcium as they are excreted from the body and thereby increase the risk of kidney stones.

If you are prone to kidney problems, your doctor may recommend a low-oxalate diet, which is 50 mg of oxalates per day. 

Foods high in oxalates (oxalic acid) include:

  • Spinach: 755 mg per ½ cup
  • Firm tofu: 235 mg per 3-ounce serving
  • Soy milk: 336 mg per 1 cup.
  • Potatoes: 97 mg per serving
  • Beets: 152 mg per 1 cup
  • Raspberries: 48 mg per 1 cup
  • Navy beans: 76 mg per ½ cup
  • Almonds: 122 mg per 1 ounce
  • Dates: 24 mg per 1 date

Other oxalate-rich foods include:

  • Bran flakes
  • Rhubarb
  • French fries
  • Nuts and nut butter
  • Soy seeds

5 tips for preventing kidney stones

1. Drink plenty of water or other fluids daily

Aim to drink at least 10-12 glasses (or 2 liters) of fluids a day, making sure 5-6 glasses are water. This will help your body flush out oxalates from your system.

2. Increase your calcium intake

Not eating enough calcium can increase the risk of kidney stone formation. This is because calcium binds to oxalates and reduces the amount of oxalates that the body absorbs.

Aim to consume 800-1200 mg of calcium per day. This can be done by eating 2-3 servings of calcium-rich foods.

One strategy is to have meals that contain both high-calcium foods and high-oxalate foods, for example, low-fat cheese with a spinach salad or yogurt with berries. This is a good way to have your favorite oxalate-rich foods while avoiding any unhealthy effects.

3. Consume vitamin C in moderation

Vitamin C produces oxalate as an end product, so consuming too much vitamin C (more than 500 mg) may be bad for you if you are prone to developing kidney stones.

4. Boil oxalate-rich vegetables

Boiling vegetables can lower their oxalate levels by more than 50%, depending on the vegetable.

5. Switch to low-oxalate alternatives

You can switch to low-oxalate foods such as:

  • Kale (alternative to spinach)
  • Bok choy (alternative to spinach)
  • Cashews (alternative to almonds)
  • Peanuts (alternative to almonds)
  • Walnuts (alternative to almonds)
  • Pumpkin seeds (alternative to soy seeds)
  • Sunflower seeds (alternative to soy seeds)
  • Sweet potato (alternative to baked potato)
  • Kidney beans (alternative to navy beans)
  • Blueberries (alternative to raspberries)
  • Blackberries (alternative to raspberries)
  • Dried figs (alternative to dates)

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Medically Reviewed on 1/5/2022
References
Image Source: iStock Images

National Kidney Foundation. Kidney Stone Diet Plan and Prevention. https://www.kidney.org/atoz/content/diet

Cleveland Clinic. Kidney Stones: Oxalate-Controlled Diet. https://my.clevelandclinic.org/health/articles/11066-kidney-stones-oxalate-controlled-diet

WebMD. Foods High in Oxalates. https://www.webmd.com/diet/foods-high-in-oxalates#2

Chai W, Liebman M. Effect of different cooking methods on vegetable oxalate content. J Agric Food Chem. 2005 Apr 20;53(8):3027-30. https://pubmed.ncbi.nlm.nih.gov/15826055/